/Engine/Source/Runtime/Core/Public/Misc/CoreDelegates.h
Requests to open a message box
static [TDelegate](API\Runtime\Core\Delegates\TDelegate)< [EAppReturnType::Type](API\Runtime\Core\GenericPlatform\EAppReturnType__Type)(EAppMsgCategory, [EAppMsgType::Type](API\Runtime\Core\GenericPlatform\EAppMsgType__Type), const [FText](API\Runtime\Core\Internationalization\FText) &, const [FText](API\Runtime\Core\Internationalization\FText) &)> ModalMessageDialog;